Drilling machine

Abstract

To provide a drilling device with high hole-forming precision.SOLUTION: A drilling device includes: a table for placing a workpiece; a spindle; a pressure foot; an air cylinder for supporting the pressure foot relative to the spindle in a relatively movable manner. The air cylinder includes: a cylinder 61 to which compressed air is supplied; a piston 71 which is coupled to the pressure foot and slides inside the cylinder; and depression means 64, 78, 77 for reducing pressure inside the cylinder. The depression means reduces pressure inside the cylinder when the air cylinder has stroked by a prescribed amount. The prescribed amount is equal to or more than an amount of dropping of the spindle when the drill rushes into the workpiece, after abutment of the pressure foot against the workpiece.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a drilling device that performs processing on a workpiece using a drill.

Background Art

[0002] Conventionally, a drilling device has been devised that rotates a drill at high speed using a spindle provided with an air bearing, and performs drilling while pressing a substrate with a pressure foot (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Thus, when performing drilling while pressing the substrate with the pressure foot, it is possible to suppress the lifting and displacement of the substrate during drilling, and improve the quality of the drilling. However, conventionally, since the pressure foot continues to press the substrate with the same pressure when the drill enters the substrate until the drilling is completed, the substrate may stretch and there may be a difference in hole position accuracy between the initial stage and the final stage of processing.

[0005] Therefore, an object of the present invention is to provide a drilling device with high drilling accuracy.

Means for Solving the Problems

[0006] One aspect of the present invention comprises a table on which a workpiece is placed, a spindle that holds a drill so as to be able to rotate at high speed, a pressure foot located below the spindle that presses the workpiece against the table, and an air cylinder that supports the pressure foot so as to be able to move relative to the spindle, wherein the air cylinder has a cylinder to which compressed air is supplied, a piston connected to the pressure foot and sliding within the cylinder, and a pressure reducing means for reducing the pressure inside the cylinder, the pressure reducing means is piston but From the maximum extrusion position A predetermined amount, Pushed The drilling apparatus is configured to reduce the pressure inside the cylinder based on the above, and the predetermined amount is greater than or equal to the amount the spindle descends from the time the pressure foot contacts the workpiece until the drill enters the workpiece. [Effects of the Invention]

[0007] According to the present invention, a drilling apparatus with high drilling accuracy can be provided. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram showing a drilling machine before drilling into a circuit board. [Figure 2] This is a schematic diagram showing a drilling machine after the circuit board has been penetrated. [Figure 3] This is a schematic diagram showing the state of the air cylinder as shown in Figure 1. [Figure 4] This is a schematic diagram showing the state of the air cylinder in Figure 2. [Modes for carrying out the invention]

[0009] The following describes a drilling apparatus according to an embodiment of the present invention with reference to the figures. In the following description, the X-axis direction and the Y-axis direction are mutually orthogonal directions based on the state of the workpiece as viewed from above, and the Z-axis direction is the direction orthogonal to these X-axis and Y-axis directions. For example, in Figure 1, the X-axis direction is the left-right direction in the drawing, the Y-axis direction is the front-back direction in the drawing, and the Z-axis direction is the up-down direction in the drawing.

[0010] [Outline configuration of a drilling machine] First, the general configuration of the drilling apparatus 1 will be explained using Figure 1. As shown in Figure 1, the drilling apparatus 1 according to this embodiment includes a table 2 that is movable along the X axis on a device base (not shown), a spindle unit 3, and a pressure foot 5. A workpiece (a printed circuit board in this embodiment) W, which is to be drilled, is placed on the table 2.

[0011] The spindle unit 3 comprises a spindle 3a that rotatably holds the drill 4, and a holder 3b that holds the spindle 3a, and is supported to be movable in the Y-axis and Z-axis directions via a cross slide and a saddle (not shown). More specifically, the spindle 3a comprises a rotor shaft having a collet chuck to which the drill 4 is attached at its tip, an air bearing that rotatably supports the rotor shaft, and a motor that rotates the rotor shaft. The air bearing supports the rotor shaft radially with a radial air bearing and axially with a thrust air bearing. The motor consists of a rotor formed on the rotor shaft and a stator positioned opposite the rotor. The spindle 3 then holds the drill 4 so that it can rotate at high speed using these rotor shaft, air bearing, and motor.

[0012] Furthermore, a pressure foot 5 is engaged with the lower side of the spindle 3a to hold down the workpiece W during drilling. The pressure foot 5 is supported by a pair of left and right air cylinders 6, 6 so as to be movable relative to the spindle 3a, and these air cylinders 6, 6 are supported by the bracket portion 31b of the holder 3b. Therefore, when the spindle unit 3 descends in the Z-axis direction, the pressure foot 5 also descends in the Z-axis direction together with the spindle unit 3, and when the spindle unit 3 descends to a predetermined height position, as shown in Figure 1, it contacts the surface of the workpiece W in advance of the drill 4 supported by the spindle 3a.

[0013] The air cylinders 6,6 are constantly supplied with compressed air at a constant pressure from the compressor 7, which acts as an air supply means, pressing the pressure foot 5 downwards. When the spindle unit 3 descends further while the lower surface of the pressure foot 5 is in contact with and pressing down on the surface of the workpiece W, the air cylinders 6,6 stroke, and only the spindle unit 3 descends while the position of the pressure foot 5 remains unchanged. As shown in Figure 2, the drill 4 supported by the spindle 3a then penetrates the workpiece W, and a hole is drilled in the workpiece W. When drilling is completed and the spindle unit 3 rises, the pressure foot 5 also rises together with the spindle unit 3 from a certain position.

[0014] [Air cylinder configuration] Next, the configuration of the air cylinders 6, 6 will be explained in detail. Figure 3 shows the state of the air cylinder 6 of the drilling machine 1 as shown in Figure 1. As shown in Figure 3, the air cylinder 6 is composed of a cylinder 61 and a piston 71 that slides inside the cylinder. The air cylinder 6 has a seal between the inner circumferential surface 62 of the cylinder 61 and the outer circumferential surface 72 of the piston 71, and a cylinder chamber 63 is formed on the side of the piston 71 opposite to the rod portion 73. Ports for supplying and exhausting compressed air are formed in the cylinder chamber 63, and when compressed air is supplied from the compressor 7 to the cylinder chamber 63, the internal pressure of the cylinder chamber 63 increases, generating a downward pressing force on the piston 71.

[0015] In this embodiment, the piston 71 comprises a rod portion 73 connected to the pressure foot 5 described above, and a piston portion 74 that slides within the cylinder 61. The piston portion 74 is a hollow cylindrical shape and comprises a bottom portion 75 to which the rod portion 73 is attached, and a peripheral wall portion 76 that forms an outer surface that slides with the inner circumferential surface 62 of the cylinder 61. It is formed to open into the cylinder chamber 63 on the opposite side of the bottom portion 75 in the axial direction (sliding direction). Furthermore, the peripheral wall portion 76 is provided with an opening 78 that connects the inside and outside of the internal space 77 of the piston portion 74.

[0016] Furthermore, an opening 64 is formed at a predetermined height position on the circumferential wall of the cylinder body 65 that forms the inner circumferential surface 62 of the cylinder 61, connecting the inside and outside of the cylinder 61. These openings 64 of the cylinder 61 and 78 of the piston 71 constitute a pressure reduction means that reduces the pressure inside the air cylinder 6 to reduce the pressing force of the pressure foot 5. More specifically, the opening 64 of the cylinder 61 and the opening 78 of the piston 71 are located at corresponding positions in the circumferential direction. At the maximum extrusion position of the piston 71 in Figure 3, the opening 64 is closed by the outer circumferential surface of the piston 71, and the opening 78 is closed by the inner circumferential surface of the cylinder 61, so that these openings 64 and 78 do not communicate with each other. In this state, the compressed air supplied from the compressor 7 cannot escape to the outside through the openings 78 and 64, so the internal pressure of the cylinder chamber 63 is not reduced through the openings 78 and 64, and the pressing force of the air cylinder 6 is at its maximum at the maximum extrusion position of the piston 71. Then, the air cylinder 6 descends together with the spindle unit 3 in this maximum extrusion position until the pressure foot 5 contacts the workpiece W.

[0017] Also, at this maximum extrusion position, a predetermined distance t is provided between the upper end position of the opening 78 of the piston 71 and the lower end position of the opening 64 of the cylinder 61. For the stroke portion of this distance t, the opening 64 of the cylinder 61 and the opening 78 of the piston 71 are not in communication, and the pressing force of the air cylinder 6 is maintained at the maximum value. In the present embodiment, this distance t is set to be at least greater than or equal to the descending distance of the spindle 3a from when the pressure foot 5 contacts the workpiece W until the tip of the drill 4 penetrates the workpiece W. Therefore, at least when the drill 4 penetrates the workpiece W, the workpiece W is pressed by the pressure foot 5 with the maximum pressing force.

[0018] Further, when the drill 4 penetrates the workpiece W and the drilling progresses to the state as shown in FIG. 2 described above, the stroke amount of the piston 71 becomes greater than or equal to the distance t. As shown in FIG. 4, the opening 64 of the cylinder 61 and the opening 78 of the piston 71 are in communication. When the opening 64 of the cylinder 61 and the opening 78 of the piston 71 are in communication, the compressed air CA in the cylinder chamber escapes to the outside of the cylinder through the openings 78 and 64, thereby being decompressed, and the pressing force of the workpiece W by the pressure foot 5 becomes smaller.

[0019] Thus, in this embodiment, the opening 64 of the cylinder 61, the opening 78 and the internal space 77 of the piston 71 each serve as an air vent hole, and these air vent holes constitute a pressure reducing means for reducing the pressure inside the cylinder based on the air cylinder 6 stroking a predetermined amount t. The above-mentioned predetermined amount t is not less than the amount of descent of the spindle 3a from when the pressure foot 5 contacts the workpiece W until the drill 4 penetrates the workpiece W. Therefore, the pressing force of the workpiece via the pressure foot 5 by the air cylinder 6 maintains the maximum pressing force at least until the drill 4 penetrates the workpiece W. Thereby, the workpiece W can be reliably held by the pressure foot 5 when the drill 4, which is when the workpiece is most likely to move violently, penetrates. Further, when drilling progresses from the time the drill 4 penetrates and the amount of descent of the spindle 3a increases, the above-mentioned air vent holes communicate and the air cylinder 6 is depressurized, and the pressing force of the workpiece W by the pressure foot 5 decreases. Thereby, during drilling, the workpiece W is always pressed with the maximum pressing force, and it is possible to prevent a difference in the hole drilling position accuracy between the initial stage and the final stage of processing, for example, due to the workpiece such as a printed circuit board extending.

[0020] In the drill processing apparatus 1 according to this embodiment, as described above, when the drill 4 penetrates the workpiece W, the workpiece W is held by the pressure foot 5 with the maximum pressing force, and thereafter, by reducing the pressing force of the workpiece W to prevent the workpiece such as a printed circuit board from extending, it is possible to accurately drill the workpiece.

Explanation of Reference Numerals

[0021] 1: Drill processing apparatus, 2: Table, 3a: Spindle, 4: Drill, 5: Pressure foot, 6: Air cylinder, 61: Cylinder, 71: Piston, 64, 77, 78: Pressure reducing means, t: Predetermined amount, W: Workpiece

Claims

1. A table on which to place the workpiece, A spindle that holds the drill so that it can rotate at high speed, A pressure foot located below the spindle presses the workpiece against the table, The system comprises an air cylinder that supports the pressure foot so as to be movable relative to the spindle, The air cylinder comprises a cylinder to which compressed air is supplied, a piston connected to the pressure foot and sliding within the cylinder, and a pressure reducing means for reducing the pressure inside the cylinder. The pressure reducing means is configured to reduce the pressure inside the cylinder based on the piston being pushed in by a predetermined amount from the maximum extrusion position, wherein the predetermined amount is greater than or equal to the amount the spindle descends from the time the pressure foot contacts the workpiece until the drill enters the workpiece. A drilling apparatus characterized by the following features.

2. The pressure reducing means is an air vent hole formed in the cylinder and the piston, When the piston is in its maximum extension position, the air vent hole of the cylinder is blocked by the piston. When the piston is pushed in by a predetermined amount from the maximum extension position, the air vent hole of the cylinder communicates with the inside of the cylinder through the air vent hole of the piston, and the pressure inside the cylinder is reduced. The drilling apparatus according to claim 1, characterized in that it is a drilling apparatus.

Images